A sprung floor is a floor that is designed to absorb impact or vibration. Such floors are used for dance and indoor sports, martial arts and physical education to enhance performance and reduce injury. Impact injuries and repetitive stress injuries are mitigated by sprung floors.
Sprung-floor requirements are similar for dance or sports. Aspects of sprung floors include: stability; balance; flatness; flexion to prevent injuries without being so soft as to cause fatigue; sufficient traction to avoid slipping without causing one's foot to twist due to excessive grip.
Common construction methods include woven slats of wood or wood with high-durometer rubber pads between the wood and sub-floor, or a combination of the woven slats with rubber pads. Some sprung floors are constructed as permanent structures while others are composed of modules that slot together and can be disassembled for transportation. When constructed, a gap is left between the sprung floor and walls to allow for expansion and contraction of the sprung-floor materials.
The surface of a sprung floor is referred to as the performance surface and may be constructed of either a natural material such as solid or engineered wood or may be synthetic such as vinyl, linoleum or other polymeric construction. The surface upon which a sprung floor is installed is referred to as the sub-floor.
Some pads or shock absorbers used in sprung-floor construction are made of rubber or elastic polymers. The term elastic polymer is commonly referred to as rubber. Elastomers are amorphous polymers having viscosity and elasticity with a high failure strain compared to other polymers. Rubber is a naturally occurring substance that is converted into a durable material through the process of vulcanization. Elastomers or elastomeric materials may be thermosets or thermoplastic. A thermoset material is formed and set with a heating process. Thermoset materials do not return to their liquid state upon re-heating. Thermoplastic materials return to a liquid state when subject to sufficient heat. Thermoplastic materials may be injection-molded while thermoset materials are commonly molded in low-pressure, foam-assisted molds or are formed in stock material that may be die-cut or machined.
Bending stiffness, also referred to as flexural rigidity, may be understood to be the result of a material's elastic modulus (E) multiplied by the area moment of inertia (I) of the beam cross-section, E*I. Bending stiffness or flexural rigidity may be measured in Newton millimeters squared (N*mm^2) A beam is also referred to as an elongate member.